Electric timepiece

ABSTRACT

AN ELECTRIC TIMEPIECE HAVING A VIBRATOR ENERGIZED BY A PIEZOELECTRIC OR ELECTROSTRICTIVE ELEMENTS. THE VIBRATOR IS MOUNTED ON A TERMINAL BOARD PROVIDED WITH A LEAD WIRE FOR CONNECTION TO SAID PIEZOELECTRIC OR ELECTROSTRICTIVE ELEMENT. THE VIBRATOR, PIEZOELECTRIC OR ELECTROSTRICTIVE ELEMENT, AND TERMINALI BOARD ARE ADAPTED TO BE MOUNTED ON THE MAIN PLATE OF THE TIMEPIECE OR REMOVED THEREFROM AS A UNIT.

KIKUO KURINO I ELECTRIC TIIIEYIECE 2 Sheets-Sheet 1 Filed Marh .12. 1970 Oct. 19, 1971 KIKUO KURINO 3,613,350

' ELECTRIC TIMEPIECE Filed March .12, 1970 2 Sheets-Sheet 2 United States Patent O1 fice' 3,613,350 ELECTRIC TIMEPIECE Kikuo Kurino, Suwa, Japan, assignor to Kabushiki Kaisha Suwa Seikosha, Tokyo, Japan Filed Mar. 12, 1970, Ser. No. 18,989 Claims priority, application Japan, Mar. 4, 1969, 44/ 22,326 Int. Cl. G04c 3/00 U.S. Cl. 58-23 TF 3 Claims ABSTRACT OF THE DISCLOSURE DESCRIPTION OF DRAWINGS FIG. 1 is a top plan view showing an electrostrictive electric timepiece;

FIG. 2 shows one embodiment according to the invention;

FIG. 3 is a sectional view of FIG. 1; and

FIG. 4 shows another embodiment.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric timepiece having an electrostrictively or piezoelectrically drivable vibrator such as a tuning fork.

One object of the invention is to provide an electric timepiece using an electrostrictively or piezoelectrically driven vibrator as a time standard.

Another object of the invention is to provide an electric timepiece wherein an electrostrictively or piezoelectrically driven vibrator directly drives the gear trains.

It is generally known that the extremely higher precision watch can be obtained by using a tuning fork as a time standard, compared with the conventionally known watch using a balance wheel and a hair spring. Several watches having tuning forks have been put into practical use.

There are two types of electro-mechanical converters, i.e., electro dynamic driving system and electrostrictive or piezoelectric driving system. In the electro dynamic driving transducer, a magnetic circuit is provided on the free end of the tines. A coil is disposed slightly spaced from the permanent magnet fixed to the vibrator. Current is applied through this coil and the vibrator is energized by the mutual induction of electric current and magnetic flux. The voltage induced in the other coil is put in the input terminal of the transistor to maintain the oscillation. Since the coil is immovably fixed to the electric circuit case, the coil and electric circuit part may be set in one case and molded. An electrostrictive driving transducer is oscillated by maintaining the oscillation in such a manner that a high dielectric electrostrictive, such as PbZrTiO is fixed with adhesives to the root portions of the tines of the tuning fork for energizing the vibrator of the tuning fork.

In watches having a tuning fork, it is sometimes re quired that the vibrator be removed from the main plate of the watch for adjustment and repair. In case the transducer is driven electromagnetically or electrodynamically, the vibrator and the transducer are arranged so as not to 3,613,350 Patented Oct. 19, 1971 vibrator and transducer are related to each other in a complicated manner. In order to operate the tuning fork electrodynamically, it is especially necessary to insert the cylindrical permanent magnet into the coil in a cup form. Thus, highly trained skill is required to take out only the vibrator with the electric circuit of the transducer being mounted on the watch. On the other hand, if the transducer is driven electrostrictively, an electrostrictive element is always attached to the vibrator to form one body with it, and therefore it is easy to mount and remove the vibrator to and from the watch plate. It also has, however, disadvantages which are as follows:

In removing and mounting the vibrator, it is necessary to remove or mount the lead wire which is soldered to the electrostrictive element. Also, the lead wire of the electrictively driven vibrator is made of insulating copper wire as thin as 0.05 mm. so as to be leak proof, and therefore it is easily broken. With such a thin copper wire, highly trained skill is required to remove the enamel coating on the end of the lead wire. It is, therefore, extremely diflicult to mount or remove the lead wire to or from the lead terminal without breaking, and for this reason the electrostrictively driven tuning fork watch has not yet been put into practice in spite of its simple structure.

The present invention seeks to eliminate the above defects and to provide an electric watch having an electrostrictively driven vibrator which is easily disassembled and assembled. This is realized by fixing the terminal board to the vibrator.

Referring to the drawings:

FIG. 1 is a top plan view of an electrostrictively driven tuning fork watch;

FIG. 2 shows one embodiment according to the invention;

FIG. 3 is a cross sectional view of FIG. 2.

In the drawings, 1 is a tuning fork vibrator. Driving electrostrictive element 2 and detecting electrostrictive element 3 are fixed to the root portions of the tines. Driving electrode lead 4 and detecting electrode lead 5 are soldered to said electrostrictive elements at one end and fixed at their other end to conductive patterns 7 and 8 respectively on terminal board 6. Patterns 7 and 8 serve as driving terminal and detecting terminal of the tuning fork respectively and are connected to the electric circuit block 9 by means of wiring materials covered with vinyl. It may be connected by thin film Be-Cu, with the end portion of Be-Cu being screw mounted to the terminal board. The terminal board is fixed to the stem 22 of the tuning 'fork by means of screw 10. The tuning fork, and the terminal board are screw mounted on the watch plate 15 by means of the screws 11 and 12.

In the construction according to the invention wherein the terminal board and the tuning fork are always fixed, it is suflicient when removing or mounting .the tuning fork, to remove or mount the screws 11 and 12 and the connecting wires 13 and 14 which are strong and hard to break. It is unnecessary to remove thin lead wires 4 and 5 which are easily broken, so handling of the vibrator is very simple.

In FIG. 4, different from FIG. 2, the tuning fork is fixed first to the terminal board 16 by means of screws 17 and 18, then the terminal board is fixed to the plate by means of screws 19, 20 and 21. It is also possible to enlargethe terminal board in FIG. 4 (larger than that of FIG. 3) to mount the electric circuit and make it replaceable as an oscillating circuit unit, including vibrator and terminal board. The terminal board can be mounted temporarily by calking, with adhesives or by inserting between the projections on the vibrator and then the circuit board and the vibrator are fixed to the main plate with screws.

As described above, the present inventionsimplifies the mounting and removal of the electrostrictive tuning fork to and from the main plate of the watch by fixing the terminal board to the electrostrictively driven vibrator and connecting thin lead wire to said terminal board. By this method, mounting and removing of the tuning fork is easily accomplished compared to the conventionally known method. It is possible to adjust, repair and replace the vibrator without requiring trained skill.

What is claimed is:

1. An electric timepiece having a main plate comprising a vibrator; a piezoelectric or electrostrictive element mounted on said vibrator for energizing said vibrator; a terminal board mounted on said vibrator; and a lead wire extending between said terminal board and said piezoelectric or electrostrictive eleemnt, whereby said vibrator, piezoelectric or electrostrictive element, terminal board and lead wire may be mounted on or removed from said timepiece main plate as a unit.

2. An electric timepiece as recited in claim 1, wherein said terminal board includes contact means in electrical connection with one end of said lead wire; said timepiece including circuit means and means connecting said circuit means to said terminal board contact means.

3. An electric timepiece as recited in claim 1, wherein said vibrator is used as a time standard; said timepiece including gear trains driven directly by said vibrator.

References Cited UNITED STATES PATENTS 3,456,137 7/1969 Ganter et a1. 5823 X 3,512,352 5/ 1970 Ito 585-23 RICHARD B. WILKINSON, Primary Examiner E. C. SIMMONS, Assistant Examiner US. Cl. X.R. 

